The Energy Wiz: Seeing (and Saving) The Light
Changes to electricity pricing may also provide new opportunities for savings due to lighting upgrades. If your lighting hasn't been upgraded since the early '80s, these options offer an even better payback. In this first of a two-part column, we'll look at why it may be time to consider the next steps in lighting efficiency.
Save 7% Just By Changing Your Lamp SpecRemember your conversion from T12 lamps and magnetic ballasts to T8 lamps and electronic ballasts? (Please don't tell me you're still using T12's!) Here's a simple way to go a step further.
General Electric (GE) Lighting recently introduced its T8 Watt Miser lamp, which provides the same lumen output as a standard T8, has the same lifetime and color quality, but consumes 2 less/4-ft tube. While limited to use on instant-start electronic ballasts, this lamp fits into existing sockets and fixtures, making it an easy relamping choice. Yes, it costs a little more (about $1 extra per lamp), but odds are that price differential will narrow (or disappear) once Osram and Phillips come out with their own versions.
At the national average power cost of about $0.08/kWh, payback on that differential occurs in about 2 years, while the lamp's lifetime remains at 6 to 10 years, depending on annual burn hours. In some high-cost areas (e.g., the Northeast and California), payback is closer to a year.
In other words, you get the opportunity to spend just as much as you normally would for lamps and power in one year, but cut your lighting power bill thereafter by about 7% at no additional cost. Smart facility managers are changing their relamping specs to use this lamp so that, over time, relamping converts their whole facility to it at no additional labor cost. For further information, go to: General Electric Lighting and look at the lamp's specs in this site's e-catalog.
Stop Overlighting Empty StairwellsAnd what about those high-rise stairwells? Just as LED exit signs became the way to go for 24-hr signage, bilevel fluorescent fixtures with built-in occupancy sensors have now proven themselves sufficiently to warrant using them in stairwells, even where efficient T8 lamps are deployed.
Studies show that stairwells in office buildings are occupied only about 10% of the time, while high-rise apartment stairwells see only about 30% occupancy. While it's never safe to fully turn off lighting where emergency egress is essential, bilevel electronic ballasts allow lamp output to be cut by 50%, 70%, or 90%, depending on the minimum safe level of lighting needed when one first enters a stairwell.
While energy savings are not as great as lumen reduction (the 90% cut in light level may still use 25% of the wattage), significant savings in wattage are nevertheless attainable.
As soon as someone enters the stairwell, occupancy sensors in nearby fixtures return light levels to normal. After a brief (e.g., 15-min) period of no occupancy, light levels are again dropped to the acceptable minimum. Even a 50% savings 70% of the time may pay back the cost of new fixtures in an acceptable time period.
As Always, Exercise CautionAll new technologies need to be well understood before expanding their application to your whole facility. While simply changing a lamp spec or a fixture may seem like an easy way to attain savings, be sure to check out any new lighting option in a test area for at least a few weeks to be sure it works for you. And remember: Never install anything smarter than the dumbest guy who must maintain it!
Next month we'll review several other new lighting technologies worth considering for high bay areas, office spaces, and where demand-response programs are available. ES